Impact of Climate Change on an R-2000 and a Net Zero Energy Home

Abstract

The impact of the predicted climate change on the energy use of a residential building is studied. For this purpose, an R-2000 home built near Montreal, Canada is simulated using TRNSYS environment based on the construction documents. In order to calibrate the model, the simulated total annual electricity use is compared with the actual energy consumption from the utility bills. The simulation results are found in agreement with the actual energy use, with less than 2% difference. The study involves four cases: (i) the R-2000 home, i.e. the Base case, in today’s climate, (ii) the Base case under the predicted climate of 2050, (iii) the Base case converted into a Net Zero Energy Home (NZEH) in today’s climate, and (iv) the NZEH in the predicted climate of 2050.

The projections in terms of monthly data for temperature, solar radiation, relative humidity, and wind speed for 2050 for Montreal are extracted from three different global climate models (CGCM2, ECHAM4, and HadCM3) with two scenarios each, A2 and B2. Hourly data is generated from this monthly data. To convert the R-2000 home into a NZEH, various energy efficiency measures and technologies are used, along with a liquid-based hybrid PV/Thermal combi-system. Finally, a complete life cycle analysis (LCA) of cost, energy, and emissions for both the houses including all their systems and components is conducted.

For the Base case, the heating loads reduce by 11 to 22%, while the cooling loads increase by 25 to 93% by the mid-century. For the NZEH, a change in the PV/T production is observed by -1 to 4% for electrical and by -10 to 1% for thermal energy, due to the climate change. The LCA comparison between the two houses indicates that although it initially costs more, the NZEH becomes cost competitive with the Base case over the life span of 50 years. In spite of 40% higher embodied energy of the NZEH, the life cycle energy for the Base case is 1.5 to almost 3 times higher than the NZEH over the 30-50 year life span. The energy payback time is found to be 9.2 years for the PV, while 7 years for the combined PV/T. The life cycle emissions are found 14.5 and 29% less for the NZEH compared to the Base case over the life spans of 40 and 50 years, respectively.